A critical examination of the turbulence instrument used in the Marsta micro-meteorological field project

A turbulence instrument described earlier (Högström, 1967), and used in an extensive micro-meteorological field project, has been examined critically. Static wind tunnel calibrations give accurate, reproducible results. Field measurements and theoretical considerations indicate complications in the dynamical situation, however. It is shown that the instrument is well suited for the measurement of the horizontal component of the wind and its rapid fluctuations. For the measurement of the turbulent fluxes of sensible heat and of water vapour a correction of order of magnitude 10% must be applied. The instrument is further shown to be unsuited for measuring the shearing stress and the variance of the vertical velocity component